Does Coenzyme Q10 (CoQ10) have adverse effects?

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Last updated: May 27, 2025View editorial policy

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From the Guidelines

CoQ10 supplementation appears to be safe with only few observed side effects, primarily gastrointestinal effects such as nausea, vomiting, diarrhea, and anorexia, as reported in the 2022 espen micronutrient guideline 1. When considering the potential negative side effects of CoQ10, it is essential to weigh the benefits against the risks. The majority of studies suggest that CoQ10 is well-tolerated, with minimal adverse effects.

  • Gastrointestinal symptoms, such as nausea, vomiting, diarrhea, and anorexia, are the most commonly reported side effects 1.
  • Higher doses of CoQ10, typically above 300mg daily, may increase the likelihood of side effects, although the evidence is not conclusive 1.
  • CoQ10 may interact with certain medications, such as blood thinners like warfarin, and individuals taking these medications should consult their healthcare provider before starting supplementation 1.
  • People with diabetes should monitor their blood sugar levels carefully when taking CoQ10, as it may affect insulin requirements 1. The typical dosage of CoQ10 ranges from 100-200mg daily, taken with food to improve absorption, as it is fat-soluble 1. Overall, the available evidence suggests that CoQ10 supplementation is generally safe, with minimal negative side effects, and can be a beneficial addition to a healthy lifestyle, particularly for individuals taking statin medications or those with decreased CoQ10 production due to age 1.

From the Research

CoQ10 Side Effects

  • The available evidence suggests that CoQ10 has low toxicity and does not induce serious adverse effects in humans 2.
  • The acceptable daily intake (ADI) of CoQ10 is 12mg/kg/day, with an observed safety level (OSL) of 1200 mg/day/person 2.
  • Clinical evidence shows that CoQ10 supplementation for prolonged periods is safe and well-tolerated 3.
  • There is no mention of significant negative side effects of CoQ10 in the available studies, with most focusing on its safety and efficacy in various health conditions 2, 3, 4, 5, 6.

Safety Profile

  • The safety profile of CoQ10 is based on animal and human data, with published reports indicating low toxicity and no serious adverse effects 2.
  • Pharmacokinetic studies suggest that exogenous CoQ10 does not influence the biosynthesis of endogenous CoQ9/CoQ10 nor does it accumulate into plasma or tissues after cessation of supplementation 2.
  • CoQ10 supplementation has been shown to reduce oxidative stress and mortality from cardiovascular causes, improve clinical outcome in patients undergoing coronary artery bypass graft surgery, and prevent the accumulation of oxLDL in arteries 3.

Overall Safety

  • Overall, the available evidence suggests that CoQ10 is highly safe for use as a dietary supplement, with a low risk of adverse effects 2, 3, 4, 5, 6.
  • The safety of CoQ10 has been evaluated in various studies, with most concluding that it is a safe and well-tolerated supplement 2, 3, 4, 5, 6.

References

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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